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tion, and where the position of the axis enables us to trace a 
circular arrangement even to the vicinity of the Poles, and to 
infer with little chance of error, that notwithstanding the 
slackened rotation, arctic and antarctic belts exist upon Jupiter 
also. 
As to the possible extent of this atmosphere, we have little 
to guide us. N o observer, however powerful may be his 
optical means, has ever recorded any deviation in the outline 
of the limb as it traverses successively the darker and brighter 
portions ; and yet a considerable depth would seem to be re- 
quired, to admit of a difference in the velocity of rotation 
between the upper and lower regions, adequate to the pro- 
duction of so persistent a streakiness. The fact that this 
streakiness affects the whiter more than the yellower parts of 
the disc may be significant as intimating that the yellow 
vapours, if such they are, are of less vertical thickness, what- 
ever may be their relative situation in the atmosphere. I 
am, as before, doubtful as to the existence of any such fading 
of the ends of the dark stripes as might arise from imperfect 
transparency in their clearer air. On some occasions I have 
believed that the North temperate belt has been fainter 
towards its extremities ; and on Jan. 20 I thought the fall- 
ing-off much more perceptible in this than in the other belts ; 
which, if such delicate variations at the extreme verge of 
optical power could be trusted, might accord with the suppo- 
sition of its greater vertical depth. At other times the whole 
of the belts preserved their tone very fairly to their extre- 
mities; and my impression is confirmed that either optical 
deficiency has vitiated some previous representations, or that 
the condition of the planet’s atmosphere has been on such 
occasions widely different from that which it has now long 
maintained. 
There seems little doubt that for a considerable time the 
North has possessed a clearer sky than the South portion of the 
planet. The coincidence with the period of summer in that 
hemisphere will be remarked : nor need the slight inclination 
of the axis be considered a bar to the natural conclusion, since, 
when the whole constitution of the globe is evidently very 
unlike our own, there is nothing forced in the supposition that 
a slight difference of inclination might be much more influ- 
ential than in our own case. At present it is a mere suggestion, 
arising from slender evidence, and requiring further observations 
for its confirmation. 
The most singular feature of the disc continues to be the 
prevalence of these elliptical areas, which it is so difficult to 
explain by any terrestrial analogy. That they are not confined 
to the equatorial region, and in fact do not there attain their 
